Hi Ayman,

Thanks for your reply. I had masses defined for all segments and no external forces were applied. Looks like the masses I had were too big (and unrealistic). When I reduced them, the inverse dynamics returned some results. Thanks for your help.

<t>I have been trying to use Anita's neck model in OpemSim and I have had a few problems, I've tried a couple workarounds but still amn't getting anywhere. Here's what I've done (sorry if its a bit long-winded)<br/> <br/> I imported the SIMM model using the Neck3dof.jnt and NeckMus.msl files. That w...

Is there a basic step by step guide as to how to add external forces to a model? I have read the tutorials and user guide but it doesn't seem to be covered in much depth.

Thanks!